It's is all in your answers. Like 'Inshal'lah,' Alhamdullu'lah and a few others, it is a most profound word. So I write here only to clarify. We sometimes forget to give them 'life.' The energy behind them can be missing. It should be a very powerful form of greeting, acknowledging that both your and your brother come come from the same spark of Light. Again, it pays homage to your true Self or God. Rather like Om Nama Shivaya or Hari Om Tat Sat.
Each has its own sweetness, according to one's various Path or leanings in life. Nice contribution, Emanate presence.